The present invention relates to electrographic recording. More particularly, it relates to an improved recording stylus for electrographic recording apparatus. In the above-identified copending application of Roger D. Erickson, there has been disclosed an electrographic recording system which includes means wherein toner powder having electrical and magnetic properties is carried from a hopper to a recording station by a rotatable drum or shell. The shell is rotated about a magnetic core structure which produces a magnetic field to hold the toner powder onto the surface of the shell as it rotates. At the recording station, a dynamic bridge is formed of the toner powder between the periphery of the drum or shell and a magnetically permeable member positioned a predetermined distance from the surface of the drum or shell. A record member is driven along a path between the drum and the permeable member with the reverse side of the record member in contact with the permeable member. An array of recording electrodes are positioned to be in an electrical contact with the toner powder in the bridge. The record member is backed up by a platen member at least a portion of which is electrically conductive. When one or more of the electrodes is energized, a conductive path is established from the electrode, through the bridge, to the surface of the recording member and the conductive back-up platen, electrically charging the dielectric surface of the recording member to deposit toner thereon.
In the system described in the copending application, it is important that the position of a styli relative to the surface of the recording medium be constant. Additionally, in order to achieve a high order of lateral fidelity, it is important that the styli be arranged in a high density array, on the order of 200 to the inch. Such a high density array presents problems of stability of positioning the styli with respect to each other and also to making electrical contacts to each stylus individually.